Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
J Infect Dis ; 221(3): 449-453, 2020 01 14.
Artículo en Inglés | MEDLINE | ID: mdl-31541571

RESUMEN

L-lactate is an abundant metabolite in a number of niches in host organisms and represents an important carbon source for bacterial pathogens such as Neisseria gonorrhoeae. In this study, we describe an alternative, iron-sulfur cluster-containing L-lactate dehydrogenase (LutACB), that is distinct from the flavoprotein L-lactate dehydrogenase (LldD). Expression of lutACB was found to be positively regulated by iron, whereas lldD was more highly expressed under conditions of iron-limitation. The functional role of LutACB and LldD was reflected in in vitro studies of growth and in the survival of N gonorrhoeae in primary cervical epithelial cells.


Asunto(s)
Proteínas Bacterianas/metabolismo , Cuello del Útero/citología , Células Epiteliales/microbiología , Gonorrea/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Viabilidad Microbiana/genética , Neisseria gonorrhoeae/enzimología , Proteínas Bacterianas/genética , Femenino , Eliminación de Gen , Regulación Bacteriana de la Expresión Génica , Gonorrea/microbiología , Humanos , Hierro/metabolismo , L-Lactato Deshidrogenasa/genética , Neisseria gonorrhoeae/genética , Neisseria gonorrhoeae/crecimiento & desarrollo , ARN Viral/genética
2.
Nucleic Acids Res ; 44(14): 6981-93, 2016 08 19.
Artículo en Inglés | MEDLINE | ID: mdl-27307602

RESUMEN

Pathogenic bacteria such as Haemophilus influenzae, a major cause of lower respiratory tract diseases, must cope with a range of electrophiles generated in the host or by endogenous metabolism. Formaldehyde is one such compound that can irreversibly damage proteins and DNA through alkylation and cross-linking and interfere with redox homeostasis. Its detoxification operates under the control of HiNmlR, a protein from the MerR family that lacks a specific sensor region and does not bind metal ions. We demonstrate that HiNmlR is a thiol-dependent transcription factor that modulates H. influenzae response to formaldehyde, with two cysteine residues (Cys54 and Cys71) identified to be important for its response against a formaldehyde challenge. We obtained crystal structures of HiNmlR in both the DNA-free and two DNA-bound forms, which suggest that HiNmlR enhances target gene transcription by twisting of operator DNA sequences in a two-gene operon containing overlapping promoters. Our work provides the first structural insights into the mechanism of action of MerR regulators that lack sensor regions.


Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Unión al ADN/metabolismo , Formaldehído/metabolismo , Haemophilus influenzae/metabolismo , Compuestos de Sulfhidrilo/metabolismo , Proteínas Bacterianas/química , Cristalografía por Rayos X , ADN Bacteriano/química , ADN Bacteriano/metabolismo , Proteínas de Unión al ADN/química , ARN Polimerasas Dirigidas por ADN/metabolismo , Regulación Bacteriana de la Expresión Génica , Haemophilus influenzae/genética , Inactivación Metabólica/genética , Cinética , Modelos Moleculares , Regiones Operadoras Genéticas/genética , Regiones Promotoras Genéticas , Unión Proteica , Relación Estructura-Actividad , Factores de Transcripción/metabolismo , Transcripción Genética
3.
Front Microbiol ; 7: 257, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26973631

RESUMEN

Formaldehyde is the simplest of all aldehydes and is highly cytotoxic. Its use and associated dangers from environmental exposure have been well documented. Detoxification systems for formaldehyde are found throughout the biological world and they are especially important in methylotrophic bacteria, which generate this compound as part of their metabolism of methanol. Formaldehyde metabolizing systems can be divided into those dependent upon pterin cofactors, sugar phosphates and those dependent upon glutathione. The more prevalent thiol-dependent formaldehyde detoxification system is found in many bacterial pathogens, almost all of which do not metabolize methane or methanol. This review describes the endogenous and exogenous sources of formaldehyde, its toxic effects and mechanisms of detoxification. The methods of formaldehyde sensing are also described with a focus on the formaldehyde responsive transcription factors HxlR, FrmR, and NmlR. Finally, the physiological relevance of detoxification systems for formaldehyde in bacterial pathogens is discussed.

4.
J Infect Dis ; 210(8): 1311-8, 2014 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-24737798

RESUMEN

Lactate is an abundant metabolite, produced by host tissues and commensal organisms, and it represents an important potential carbon source for bacterial pathogens. In the case of Neisseria spp., the importance of the lactate permease in colonization of the host has been demonstrated, but there have been few studies of lactate metabolism in pathogenic Neisseria in the postgenomic era. We describe herein the characterization of genome-annotated, respiratory, and substrate-level lactate dehydrogenases (LDHs) from the obligate human pathogen Neisseria gonorrhoeae. Biochemical assays using N. gonorrhoeae 1291 wild type and isogenic mutant strains showed that cytoplasmic LdhA (NAD(+)-dependent D-lactate dehydrogenase) and the membrane-bound respiratory enzymes, LdhD (D-lactate dehydrogenase) and LldD (L-lactate dehydrogenase) are correctly annotated. Mutants lacking LdhA and LdhD showed greatly reduced survival in neutrophils compared with wild type cells, highlighting the importance of D-lactate metabolism in gonococcal survival. Furthermore, an assay of host colonization using the well-established human primary cervical epithelial cell model revealed that the two respiratory enzymes make a significant contribution to colonization of and survival within the microaerobic environment of the host. Taken together, these data suggest that host-derived lactate is critical for the growth and survival of N. gonorrhoeae in human cells.


Asunto(s)
Cuello del Útero/citología , Células Epiteliales/microbiología , Lactato Deshidrogenasas/metabolismo , Neisseria gonorrhoeae/enzimología , Neutrófilos/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , ADN Bacteriano/genética , Femenino , Regulación Bacteriana de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Humanos , Lactato Deshidrogenasas/genética , Mutación
5.
Antioxid Redox Signal ; 18(7): 743-55, 2013 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-22937752

RESUMEN

AIM: The glutathione-dependent AdhC-EstD formaldehyde detoxification system is found in eukaryotes and prokaryotes. It is established that it confers protection against formaldehyde that is produced from environmental sources or methanol metabolism. Thus, its presence in the human host-adapted bacterial pathogen Neisseria meningitidis is intriguing. This work defined the biological function of this system in the meningococcus using phenotypic analyses of mutants linked to biochemical and structural characterization of purified enzymes. RESULTS: We demonstrated that mutants in the adhC and/or estD were sensitive to killing by formaldehyde. Inactivation of adhC and/or estD also led to a loss of viability in biofilm communities, even in the absence of exogenous formaldehyde. Detailed biochemical and structural analyses of the esterase component demonstrated that S-formylglutathione was the only biologically relevant substrate for EstD. We further showed that an absolutely conserved cysteine residue was covalently modified by S-glutathionylation. This leads to inactivation of EstD. INNOVATION: The results provide several conceptual innovations. They provide a new insight into formaldehyde detoxification in bacteria that do not generate formaldehyde during the catabolism of methanol. Our results also indicate that the conserved cysteine, found in all EstD enzymes from humans to microbes, is a site of enzyme regulation, probably via S-glutathionylation. CONCLUSION: The adhc-estD system protects against formaldehyde produced during endogenous metabolism.


Asunto(s)
Aldehído Oxidorreductasas/metabolismo , Biopelículas/efectos de los fármacos , Farmacorresistencia Bacteriana/efectos de los fármacos , Formaldehído/farmacología , Neisseria meningitidis/efectos de los fármacos , Neisseria meningitidis/metabolismo , Tioléster Hidrolasas/metabolismo , Neisseria meningitidis/enzimología , Neisseria meningitidis/crecimiento & desarrollo , Relación Estructura-Actividad
6.
Infect Immun ; 80(3): 1065-71, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22184419

RESUMEN

NGO0579 is annotated copA in the Neisseria gonorrhoeae chromosome, suggesting that it encodes a cation-transporting ATPase specific for copper ions. Compared to wild-type cells, a copA mutant was more sensitive to killing by copper ions but not to other transition metals. The mutant also accumulated a greater amount of copper, consistent with the predicted role of CopA as a copper efflux pump. The copA mutant showed a reduced ability to invade and survive within human cervical epithelial cells, although its ability to form a biofilm on the surface of these cells was not significantly different from that of the wild type. In the presence of copper, the copA mutant exhibited increased sensitivity to killing by nitrite or nitric oxide. Therefore, we concluded that copper ion efflux catalyzed by CopA is linked to the nitrosative stress defense system of Neisseria gonorrhoeae. These observations suggest that copper may exert its effects as an antibacterial agent in the innate immune system via an interaction with reactive nitrogen species.


Asunto(s)
Proteínas Bacterianas/metabolismo , Cobre/toxicidad , Eliminación de Gen , Neisseria gonorrhoeae/metabolismo , Estrés Fisiológico , Proteínas Bacterianas/genética , Células Cultivadas , Cobre/metabolismo , Células Epiteliales/microbiología , Humanos , Viabilidad Microbiana/efectos de los fármacos , Neisseria gonorrhoeae/efectos de los fármacos , Neisseria gonorrhoeae/genética , Óxido Nítrico/toxicidad , Nitritos/toxicidad , Virulencia , Factores de Virulencia/genética , Factores de Virulencia/metabolismo
7.
Adv Microb Physiol ; 58: 1-22, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21722790

RESUMEN

Recognition of the diversity of transcriptional regulators of the MerR family has increased considerably over the last decade and it has been established that not all MerR-like regulators are involved in metal ion recognition. A new type of MerR-like regulator was identified in Neisseria gonorrhoeae that is distinct from metal-binding MerR proteins. This novel transcription factor, the Neisseria merR-like regulator (NmlR) is related to a large and diverse group of MerR-like regulators. A common feature of the majority of the genes encoding the nmlR-related genes is that they predicted to control the expression of adhC, which encodes a glutathione-dependent alcohol dehydrogenase. The function of the NmlR regulon appears to be to defend the bacterial cell against carbonyl stress and in some cases nitrosative stress. A potential role for NmlR in bacterial pathogenesis has been identified in Neisseria gonorrhoeae and Streptococcus pneumoniae. Although it is not known how NmlR is activated it is suggested that conserved cysteine residues may be involved in thiol-based signaling.


Asunto(s)
Proteínas Bacterianas/metabolismo , Proteínas de Unión al ADN/metabolismo , Neisseria gonorrhoeae/genética , Regulón , Estrés Fisiológico , Aldehído Oxidorreductasas/metabolismo , Animales , Proteínas Bacterianas/genética , Células Cultivadas , Proteínas de Unión al ADN/genética , Células Epiteliales/microbiología , Esterasas/metabolismo , Regulación Bacteriana de la Expresión Génica , Genes Bacterianos , Humanos , Neisseria gonorrhoeae/metabolismo , Conformación Proteica , Análisis de Secuencia de ADN , Transducción de Señal , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/metabolismo , Transcripción Genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...